<container>
  <row>
    <columns>
      <center>
        <img src="http://placehold.it/800x300" alt="" class="thumbnail">
      </center>
    </columns>
  </row>
  <row>
    <columns>
      <center>
        <img src="http://placehold.it/300x300" alt="" class="thumbnail">
      </center>
    </columns>
  </row>
  watch out for smacing issues on the full width thumbnails. The right side spacing should match left.
  <row>
    <columns small="6">
      <img src="http://placehold.it/300x300" alt="" class="thumbnail">
    </columns>
    <columns small="6">
      <img src="http://placehold.it/300x300" alt="" class="thumbnail">
    </columns>
  </row>
  <row>
    <columns large="6">
      <img src="http://placehold.it/300x300" alt="" class="thumbnail">
    </columns>
    <columns large="6">
      <img src="http://placehold.it/300x300" alt="" class="thumbnail">
    </columns>
  </row>
</container>
